reports: cleaned up a few methods in report-collectors

Author:    Peter Broadbery <p.broadbery@gmail.com>

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23029 57a11ea4-9604-0410-9ed3-97b8803252fd
Refactor so that we don't have to call gnc:progress functions while creating a report

Author:    Peter Broadbery <p.broadbery@gmail.com>

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23030 57a11ea4-9604-0410-9ed3-97b8803252fd